When an instance is removed, its status become `TERMINATED`.
As stated in [GCE Documentation](https://developers.google.com/compute/docs/instances#checkmachinestatus):
> TERMINATED - The instance either failed for some reason or was shutdown. This is a permanent status, and the only way to repair the instance is to delete and recreate it.
So we need to ignore instances with such a status.
Closes#3.
-----------------
The GCE discovery can also filter machines to include in the cluster based on tags using `discovery.gce.tags` settings.
For example, setting `discovery.gce.tags` to `dev` will only filter instances having a tag set to `dev`. Several tags
set will require all of those tags to be set for the instance to be included.
One practical use for tag filtering is when an GCE cluster contains many nodes that are not running
elasticsearch. In this case (particularly with high ping_timeout values) there is a risk that a new node's discovery
phase will end before it has found the cluster (which will result in it declaring itself master of a new cluster
with the same name - highly undesirable). Adding tag on elasticsearch GCE nodes and then filtering by that
tag will resolve this issue.
Add your tag when building the new instance:
```sh
gcutil --project=es-cloud addinstance myesnode1 --service_account_scope=compute-rw --persistent_boot_disk \
--tags=elasticsearch,dev
```
Then, define it in `elasticsearch.yml`:
```yaml
cloud:
gce:
project_id: es-cloud
zone: europe-west1-a
discovery:
type: gce
gce:
tags: elasticsearch, dev
```
Closes#2.
Google Compute Engine VM discovery allows to use the google APIs to perform automatic discovery (similar to multicast in non hostile
multicast environments). Here is a simple sample configuration:
```yaml
cloud:
gce:
project_id: <your-google-project-id>
zone: <your-zone>
discovery:
type: gce
```
How to start (short story)
--------------------------
* Create Google Compute Engine instance
* Install Elasticsearch
* Install Google Compute Engine Cloud plugin
* Modify `elasticsearch.yml` file
* Start Elasticsearch
Closes#1.
